The “not formatted error” message generally indicates hard disk problems. This can occur for many different reasons including a computer virus, hard drive problem, power surge, or problems with the operating system. If you receive this type of error message, it is important that you act carefully to keep your important data safe.

1. Do NOT say "yes" to format the drive.

2. Do NOT attempt to write anything new on this hard drive.

3. Download data recovery software to help you. There are many data recovery tools out there. But, no all of them could be efficient and useful enough. You should pay much attention to opt for a proper one.

There are many drive data recovery freeware online that could works efficiently to get your data back, such Recuva, EaseUs Data RecoveryandiCare Data Recovery Free, etc.